Flexible heat transfer structure

ABSTRACT

A heat transfer structure, including: a plurality of layers of graphite material each having a shape selected for providing a thermal path between a hotspot in an electronic device and a heat dissipating structure of the electronic device; and a set of intervening bonding layers for coupling together the layers of graphite material such that the heat transfer structure has a flexible body for avoiding mechanical stress on the hotspot when the heat transfer structure is coupled between the hotspot and the heat dissipating structure.

BACKGROUND

An electronic device can include components that generate heat. A component that generates heat in an electronic device can be referred to as a hotspot. A hotspot in an electronic device can negatively impact the functioning of the electronic device. An electronic device can include a heat dissipating structure, e.g., a housing or heat sink, for dissipating heat generated by hotspots in the electronic device.

A hotspot in an electronic device can be located a distance away from a heat dissipating structure. A metal, e.g., copper, bridge structure can be used to transfer heat from a hotspot to a heat dissipating structure located a distance away from the hotspot. A metal bridge structure can place mechanical stress on components in an electronic device, which can negatively impact the functioning of the electronic device.

SUMMARY

In general, in one aspect, the invention relates to a heat transfer structure for an electronic device. The can include: a plurality of layers of graphite material each having a shape selected for providing a thermal path between a hotspot in the electronic device and a heat dissipating structure of the electronic device; and a set of intervening bonding layers for coupling together the layers of graphite material such that the heat transfer structure has a flexible body for avoiding mechanical stress on the hotspot when the heat transfer structure is coupled between the hotspot and the heat dissipating structure.

In general, in another aspect, the invention relates to a method for heat transfer in an electronic device. The method can include: forming a plurality of layers of graphite material each having a shape selected for providing a thermal path between a hotspot in the electronic device and a heat dissipating structure of the electronic device; and bonding together the layers of graphite material such that the heat transfer structure has a flexible body for avoiding mechanical stress on the hotspot when the heat transfer structure is coupled between the hotspot and the heat dissipating structure.

Other aspects of the invention will be apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements.

FIG. 1 is a perspective view of a heat transfer structure installed in an electronic device in one or more embodiments.

FIG. 2 is a perspective view of a heat transfer structure in one or more embodiments.

FIG. 3 is a perspective view of a heat transfer structure showing how its layers of graphite material and intervening bonding layers enable flexing and bending.

FIG. 4 is a perspective view of a heat transfer structure installed in an electronic device in another embodiment.

FIG. 5 is a perspective view of a heat transfer structure installed in an electronic device in yet another embodiment.

FIG. 6 illustrates a method for heat transfer in an electronic device in one or more embodiments.

DETAILED DESCRIPTION

Reference will now be made in detail to the various embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Like elements in the various figures are denoted by like reference numerals for consistency. While described in conjunction with these embodiments, it will be understood that they are not intended to limit the disclosure to these embodiments. On the contrary, the disclosure is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the disclosure as defined by the appended claims. Furthermore, in the following detailed description of the present disclosure, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be understood that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, components, have not been described in detail so as not to unnecessarily obscure aspects of the present disclosure.

FIG. 1 is a perspective view of a heat transfer structure 10 installed in an electronic device 12 in one or more embodiments. The heat transfer structure 10 includes multiple layers of graphite material each having a shape selected for providing a thermal path between a hot spot 14 in the electronic device 12 and a heat dissipating structure 16 of the electronic device 12.

The hot spot 14 in this example is an optical fiber connector mounted on a printed circuit board in the electronic device 12. For example, the electronic device can be a communication hub, switch, router, bridge, repeater, etc. The optical fiber connector can generate heat when converting an optical signal into an electrical signal.

The heat dissipating structure 16 in this example is a housing of the electronic device 12. In other embodiments, the heat dissipating structure 16 can be a heat sink for one or more electronic components on a printed circuit board in the electronic device 12.

In the embodiment of FIG. 1, the heat transfer structure 10 is positioned to carry heat away from the hotspot 14 to a pair opposing walls 16 a-16 b of the housing of the electronic device 12. A pair of respective bent ends 10 a-10 b of the heat transfer structure 10 can be thermally coupled to the inner surfaces of the respective opposing walls 16 a-16 b using a pressure sensitive adhesive, or an adhesive resin. Alternatively, a mechanism, e.g., slots, grooves, clips, etc. can be used to enable attachment and detachment of the respective bent ends 10 a-10 b of the heat transfer structure 10 to and from the inner surfaces of the respective opposing walls 16 a-16 b.

In one or more embodiments, the heat transfer structure 10 can include 5 layers of 32 micrometers thick graphite sheets bonded to each other by intervening 10-micrometer double-sided pressure sensitive adhesive tape. The adhesive areas of each bent end 10 a-10 b can measure 15 millimeters by 15 millimeters of pressure sensitive adhesive tape. The heat transfer structure 10 in this configuration can decrease a temperature of the hotspot 14 of 129 degrees C. by approximately 41 degrees C.

FIG. 2 is a perspective view of the heat transfer structure 10 in one or more embodiments. The heat transfer structure 10 includes multiple layers 20 of graphite material and a set of intervening bonding 22 for coupling together the layers 20 of graphite material. The layers 20 of graphite material and the intervening bonding layers 22 yield a flexible body for the heat transfer structure 10. There can be any number of the layers 20 in the heat transfer structure 10. The intervening bonding layers 22 can be a flexible bonding material selected to allow flexing of the heat transfer structure 10. The intervening bonding layers 22 can be formed using a pressure sensitive adhesive, an adhesive resin, etc.

FIG. 3 is a perspective view of the heat transfer structure 10 in one or more embodiments showing how the layers 20 of graphite material and the intervening bonding layers 22 enable flexing and bending of the heat transfer structure 10. Bending can facilitate the installation of the heat transfer structure 10 between the hot spot 14 and the heat dissipating structure 16. The flexibility of the heat transfer structure 10 can help avoid mechanical stress on the hot spot 14 when the heat transfer structure 10 is installed, removed, manipulated, etc. For example, in embodiments in which the hot spot 14 is an optical fiber connector mounted on a printed circuit board, the flexibility of the heat transfer structure 10 can help avoid mechanical stress on the optical fiber connector and the printed circuit board.

In the embodiment shown in FIG. 3, the heat transfer structure 10 includes a pair of island structures 30-32 formed through the layers 20 of graphite material and the intervening bonding layers 22. The island structures 30-32 maintain a high thermal conductivity for the heat transfer structure 10 by enabling high thermal conduction between the layers 20. The island structures 30-32 can be formed from a material having high thermal conductivity, e.g., copper, silver, other metals, metal alloys, etc. The island structures 30-32 can be formed from a thermal compound. The island structures 30-32 can be formed in the heat transfer structure 10 at positions selected for providing thermal coupling to the hot spot 14 and the heat dissipating structure 16 of the electronic device 12, respectively.

FIG. 4 is a perspective view of the heat transfer structure 10 for the electronic device 12 in another embodiment. The heat transfer structure 10 in this embodiment is positioned to carry heat away from the hotspot 14 to an upper wall 16 d of the housing of the electronic device 12. A pair of respective bent ends 10 c-10 d of the heat transfer structure 10 can be thermally coupled to the hot spot 14 and the inner surface of the upper wall 16 d, respectively, using a pressure sensitive adhesive, an adhesive resin, etc. Alternatively, a mechanism, e.g., slots, grooves, clips, etc. can be used to enable attachment and detachment of the bent end 10 d of the heat transfer structure 10 to and from the inner surface of the upper wall 16 d.

In an example of the configuration shown in FIG. 4, the heat transfer structure 10 can include 5 layers of 32 micrometers thick graphite sheets bonded to each other by intervening 10-micrometer double-sided pressure sensitive adhesive tape. The adhesive areas of each bent end 10 c-10 d can measure 15 millimeters by 15 millimeters of pressure sensitive adhesive tape. The heat transfer structure 10 in this configuration can decrease the temperature of the hotspot 14 of 125 degrees C. by approximately 40 degrees C.

FIG. 5 is a perspective view of the heat transfer structure 10 for the electronic device 12 in yet another embodiment. The heat transfer structure 10 in this embodiment is positioned to carry heat away from the hotspot 14 to a sidewall 16 e of the housing of the electronic device 12. A bent end 10 e of the heat transfer structure 10 can be thermally coupled the inner surface of the sidewall 16 e using a pressure sensitive adhesive, an adhesive resin, etc. Alternatively, a mechanism, e.g., slots, grooves, clips, etc. can be used to enable attachment and detachment of the bent end 10 e to and from the inner surface of the sidewall 16 e. A flat end 10 f of the heat transfer structure 10 can be thermally coupled the hotspot 14 using a pressure sensitive adhesive, an adhesive resin, etc.

In an example of the configuration shown in FIG. 5, the heat transfer structure 10 can include 5 layers of 32 micrometers thick graphite sheets bonded to each other by intervening 10-micrometer double-sided pressure sensitive adhesive tape. The adhesive areas of the ends 10 e-10 f can each measure 15 millimeters by 15 millimeters of pressure sensitive adhesive tape. The heat transfer structure 10 in this configuration can decrease the temperature of the hotspot 14 of 125 degrees C. by approximately 40 degrees C.

FIG. 6 illustrates a method for heat transfer in an electronic device in one or more embodiments. While the various steps in this flowchart are presented and described sequentially, one of ordinary skill will appreciate that some or all of the steps can be executed in different orders and some or all of the steps can be executed in parallel. Further, in one or more embodiments, one or more of the steps described below can be omitted, repeated, and/or performed in a different order. Accordingly, the specific arrangement of steps shown in FIG. 6 should not be construed as limiting the scope of the invention.

At step 650, a plurality of layers of graphite material are formed, each having a shape selected for providing a thermal path between a hotspot in the electronic device and a heat dissipating structure of the electronic device. Step 650 can include cutting the layers from a synthetic graphite sheet. The dimensions and shape of the cuts and the number of layers can be adapted to the distance between the hotspot and the heat dissipating structure.

At step 660, the layers of graphite material are bonded together such that the heat transfer structure has a flexible body for avoiding mechanical stress on the hotspot when the heat transfer structure is coupled between the hotspot and the heat dissipating structure. Step 760 can applying a pressure sensitive adhesive or an adhesive resin between the layers.

While the foregoing disclosure sets forth various embodiments using specific diagrams, flowcharts, and examples, each diagram component, flowchart step, operation, and/or component described and/or illustrated herein may be implemented, individually and/or collectively, using a range of processes and components.

The process parameters and sequence of steps described and/or illustrated herein are given by way of example only. For example, while the steps illustrated and/or described herein may be shown or discussed in a particular order, these steps do not necessarily need to be performed in the order illustrated or discussed. The various example methods described and/or illustrated herein may also omit one or more of the steps described or illustrated herein or include additional steps in addition to those disclosed.

While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the invention as disclosed herein. 

What is claimed is:
 1. A heat transfer structure for an electronic device, comprising: a plurality of layers of graphite material each having a shape selected for providing a thermal path between a hotspot in the electronic device and a heat dissipating structure of the electronic device; and a set of intervening bonding layers for coupling together the layers of graphite material such that the heat transfer structure has a flexible body for avoiding mechanical stress on the hotspot when the heat transfer structure is coupled between the hotspot and the heat dissipating structure.
 2. The heat transfer structure of claim 1, wherein the hotspot is an optical connector on a printed circuit board in the electronic device.
 3. The heat transfer structure of claim 2, wherein the optical connector is thermally coupled to the heat transfer structure via a pressure sensitive adhesive.
 4. The heat transfer structure of claim 1, wherein the heat transfer structure is coupled to the heat dissipating structure via a pressure sensitive adhesive.
 5. The heat transfer structure of claim 1, wherein the heat transfer structure is coupled to the heat dissipating structure via a detachable mechanism.
 6. The heat transfer structure of claim 1, wherein the heat dissipating structure is a heat sink in the electronic device.
 7. The heat transfer structure of claim 1, wherein the heat dissipating structure is a housing for the electronic device.
 8. The heat transfer structure of claim 7, wherein a pair of respective bent ends of the heat transfer structure are respectively thermally coupled to a pair of respective opposing wall of the housing.
 9. The heat transfer structure of claim 7, wherein a pair of respective bent ends of the heat transfer structure are respectively thermally coupled to a wall of the housing and the hotspot.
 10. The heat transfer structure of claim 7, wherein a flat end and a bent end of the heat transfer structure are respectively thermally to the hotspot and a wall of the housing.
 11. A method for heat transfer in an electronic device, comprising: forming a plurality of layers of graphite material each having a shape selected for providing a thermal path between a hotspot in the electronic device and a heat dissipating structure of the electronic device; and bonding together the layers of graphite material such that the heat transfer structure has a flexible body for avoiding mechanical stress on the hotspot when the heat transfer structure is coupled between the hotspot and the heat dissipating structure.
 12. The method of claim 11, wherein forming a plurality of layers of graphite material comprises forming the layers each having a shape selected for providing a thermal path between an optical connector in the electronic device and a heat dissipating structure of the electronic device.
 13. The method of claim 12, further comprising thermally coupling the optical connector to the heat transfer structure via a pressure sensitive adhesive.
 14. The method of claim 11, further comprising thermally coupling the heat transfer structure to the heat dissipating structure via a pressure sensitive adhesive.
 15. The method of claim 11, further comprising thermally coupling the heat transfer structure to the heat dissipating structure via a detachable mechanism.
 16. The method of claim 11, further comprising thermally coupling the heat transfer structure to a heat sink in the electronic device.
 17. The method of claim 11, further comprising thermally coupling the heat transfer structure to a housing for the electronic device.
 18. The method of claim 17, further comprising forming a pair of respective bent ends of the heat transfer structure and thermally coupling the respective bent ends to a pair of respective opposing wall of the housing.
 19. The method of claim 17, further comprising forming a pair of respective bent ends of the heat transfer structure and thermally coupling the respective bent ends to a wall of the housing and the hotspot.
 20. The method of claim 17, further comprising forming a flat end and a bent end of the heat transfer structure and thermally coupling the flat end and the bent end to the hotspot and a wall of the housing, respectively. 